Control system for an ejector bucket



Dec. 16, 1969 T, e. CAMPBELL CONTROL SYSTEM FOR AN EJECTOR BUCKET 4 Sheets-Sheet 1 Filed Oct. 9, 196'? INVENTOR.

TREVOR G. CAMPBELL BY 9W j -mw P 'i {2y I J74 Z TORNEYS Dec. 16, 1969 'r. G. CAMPBELL CONTROL SYSTEM FOR AN EJECTOR BUCKET 4 Sheets-Sheet 2 Filed Oct. 9, 196

INVENTOR. TREVOR G. CAMPBELL BY wwfl, 24,?

ATTORNEYS 6, 1969 T. G. CAMPBELL CONTROL SYSTEM FOR AN EJECTOR BUCKET Filed oci. 9, 1967 4 Sheets-Sheet 3 momson 9:: 20mm INVENTOR.

TREVOR G. CAMPBELL ATTOEYS Dec. 16, 1969 T. G. CAMPBELL 3,484,010

CONTROL SYSTEM FOR AN EJECTOR BUCKET I Filed Oct. 9, 1967 4 Sheets-Sheet 4 INVENTOR. TREVOR G. CAMPBELL 2 I ATTORNEYS United States Patent Ofiice BAMfiW Patented Dec. 16, 1969 3,484,010 CONTROL SYSTEM FUR AN EJIECTOR BUCKET Trevor (L Campbell, Peoria County, ilk, assignor to Caterpillar Tractor (30., Peoria, 111., a corporation of Caiifornia Filed 0st. 9, 1967, Ser. No. 673,552 Int. Cl. EOZf 3/81, 3/84; 1360p 1/04 US. Cl. 214-767 9 Claims ABSTRACT OF THE DTSCLQSURE CROSS-REFERENCES TO RELATED US.

PATENTS The present invention is described with exemplary reference to US. patent application Ser. No. 691,862 entitled Ejector Mechanism for Loader Buckets, filed Nov. 3, 1966, now Patent No. 3,426,928, by Trevor G. Campbell and assigned to the assignee of the present invention.

The present invention provides an ejector control sysem for an ejector bucket. The ejector bucket is of a type supported by lift arms from a loader vehicle and having tilt and lift control systems and actuating means for varying the tilt position and elevation of the bucket respectively. In the prior art, the hydraulic motor for posiiioning the ejector was controlled by a valve and actuating means independent of the tilt and lift controls. For ejection, the operator was required to raise the bucket to eject height, tilt the bucket forwardly and then move his hand to an ejector lever to actuate the ejector. This control system is relatively ineflicient and time consuming because of the manipulations required of the operator. An additional disadvantage arises since the ejector, being independently controlled, could be actuated at any time. For example, with the bucket racked back in its carry position, accidental actuation of the ejector would cause the load in the bucket to be partly ejected over the rear of the bucket onto the loader vehicle.

The present invention overcomes these problems by associating the ejector controls with the other bucket controls to permit more efficient ejector operation and to prevent accidental actuation of the ejector.

Accordingly, it is an object of the present invention to incorporate the ejector actuating means with the tilt actuating means to permit simultaneous operation by the operator and to provide lockout means which permit ejection only when the bucket is tilted to a suitable position for ejection.

It is another object to additionally provide override means which permit ejection at any time while the bucket is being tilted forwardly.

Other objects and advantages of the present invention are made apparent from the following description and the accompanying drawings, wherein:

FIG. 1 is a side view in elevation of the forward portion of a loader vehicle having an ejector bucket;

FIG. 2 is a fragmentary view of the tilt and lift control levers for the bucket;

FIG. 3 is an enlarged view of one of the hydraulic jacks for controlling tilt position of the bucket with a lockout switch disposed on the jack;

FIG. 4 is a fragmentary illustration of the tilt and lift levers each including actuating and return means for the ejector along with override means associated with the tilt lever;

FIG. 5 is a fragmentary illustration, partly in section and partly schematic, of the actuating and return switches of FIG. 4; and

FIGS. 6 and 7 illustrate alternate embodiments of an electrical and hydraulic circuit for controlling the ejector according to the ejector actuating and return switches.

Although the present ejector control system is described with particular reference to an ejector bucket of the type set forth in the above mentioned patent application Ser. No. 591,862, now Patent No. 3,426,928, it will be readily apparent that the ejector control system may also be employed with other types of ejector buckets as well.

The forward end of a bucket loader is illustrated in FIG. 1 with an ejector bucket 11 pivotally mounted upon a pair of lift arms, one of which is illustrated at 12. The ejector bucket is of the type described in US. patent application Se.. No. 591,862, now Patent No. 3,426,928 and has an ejector assembly 13 which is pivotally mounted on the bucket at 14 and is positioned by a double acting hydraulic jack 16. Extension of the ejector jack causes forward traversal of the ejector for ejection of material from the bucket while retraction of the jack returns the ejector to its position at the rear of the bucket for loading. The bucket is illustrated in FIG. 1 tilted to a position suitable for loading at ground level and for ejection when the bucket is raised on its lift arms. The bucket is alternately illustrated at a phantom position 11' where it is raised to a suitable carry height after having been racked back to carry position. A double acting tilt jack 17 is connected to each lift arm and the vehicle by tilt linkage 18 and to the bucket by a link 19. A hydraulic lift jack 21 is pivotally connected between the vehicle and each lift arm to control the elevation of the bucket. Operation of the tilt jacks and the lift jacks are controlled by the operator through levers 22 and 23 respectively. The construction and operation of the above components are well known in the prior art, for example, in the patent application cited above.

The present invention rovides ejector actuating means 24 incorporated with the tilt control lever 22 (see FIG. 4) so that the operator may initiate ejection with his hand on the tilt control lever. Lockout means 26 (see FIG. 3) are associated with the ejector actuating means 24 in a manner described below and are preferably mounted upon one of the tilt jacks 17 to prevent ejection except when the bucket is tilted to a position suitable for ejection. Override means 27 (FIGS. 4 and 6) are preferably associated with the tilt control lever and, in combination wi h the ejector control system described below, permit ejection at anv time when the bucket is being tilted forwardly.

To describe the above components in greater detail and to describe additional features provided by the present invention, an ejector control system, which is partly hydraulic and partly electrical, is illustrated schematically in FIG. 6. A three-position valve 28 has a fluid inlet conduit 32. The valve 28 communicates with the head of the ejector jack by a conduit 29 and with the rod end of the ejector jack by a conduit 31. The position of the ejector control valve is selected according to a cylinder 33 containing a slidable piston 34 which is connected to the control valve by a rod 36. Retraction of the rod 36 into the cylinder positions the ejector control valve to direct fluid to the head end of the ejector jack for ejection. Extension of the rod 36 from the cylinder positions the ejector control valve to direct fluid to the rod end of the ejector jack so that the ejector is returned to its position at the rear of the bucket (see FIG. 1) The ejector control valve is spring centered so that, in the absence of fluid forces acting upon cylinder 33, the control valve assumes a hold position to maintain the ejector in a fixed position.

Operation of the cylinder 33 is controlled by first and second valves 37 and 38 which are communicated respectively with the rod end and the head end of the slave cylinder by conduits 39 and 41. Both valves are also communicated with a fluid source and a fluid drain by conduits 42 and 43 respectively. The valves are spring loaded and tend into a position where they communicate both ends of the cylinder 33 to drain. Shifting of either valve communicates its respective end of the cylinder 33 with hydraulic fluid to result in repositioning of the ejector control valve and the ejector jack as discussed above.

Operation of each valve 37 or 38 is controlled by the electrical portion of the control system and that portion of the circuit which initiates ejection by shifting the first valve 37 is described first. The ejection actuating means 24 is preferably a spring loaded button switch which is mounted upon the tilt lever as shown in FIG. 4 and which is illustrated in greater detail in FIG. 5. To further facilitate operator control over the ejector, a similar ejector actuating switch is indicated at 24 in FIGS. 4, and 6 and is mounted upon the lift control lever so that the operator can initiate ejection while having his hand upon either the tilt or lift control lever. Referring again to FIG. 6, the two ejector actuating switches are in electrically parallel relation and are connected to a battery 44 through the lockout switch 26. The lockout switch is a proximity switch mounted upon one of the tilt jacks as illustrated in FIGS. 1 and 3 and is of a conventional type having a dry reed switch balanced between two permanent magnets (not shown). The switch is normally open and when a metal target is passed in front of the switch, magnetic flux from the front magnet is interrupted allowing the rear magnet to close the switch and complete the circuit. The metal target for the lockout switch 26 is a steel bar 46 mounted upon a trombone member 47 which is secured to the rod of the tilt jack. As best shown in FIGS. 1 and 3, the steel bar 46 passes in front of and closes the lockout switch when the bucket is in a general horizontal position (see the solid line illustration of the bucket in FIG. 1). Racking the bucket back to its carry position, shown in broken lines in FIG. 1 causes the steel bar to move away from the lockout switch as shown in broken lines in FIG. 3. The lockout switch is now open and will not permit current to pass. Referring again to FIG. 6, the parallel ejection switches 24 and 24' are connected to a first solenoid 48 through a relay switch 49. The first solenoid is connected to the first valve 37 so that closing of either switch 24 or 24' energizes the relay 49 which in turn energizes the first solenoid and shifts the first valve. As described above, shifting of the first valve 37 initiates action of the bucket ejector through the cylinder 33, ejector control valve and ejector jack. However, before closing of either switch 24 or 24' can energize the relay, the lockout switch 26 must be closed to complete the circuit with the battery. As described with reference to FIGS. 1 and 3, the lockout switch 26 is closed only when the bucket is in a suitable position for ejection so that accidental operation of the ejector is normally prevented when the bucket is otherwise positioned. The relay 49 is necessary only because the current carrying capacity of the proximity lock-out switch 26 is insufiicient to directly energize the solenoid 48. 'If the proximity switch and the actuating switches 24 and 24' were of a more expensive type having higher current carrying capacity, the relay could be omitted from the circuit.

To return the ejector to its position at the rear of the bucket, similar parallel button switches 51 and 51 are disposed on the tilt and lift levers respectively so that the operator can initiate ejector return while leaving his hand on either the tilt or lift control lever (see FIGS. 4 and 5). Referring again to FIG. 6, the parallel switches 51 and 51 are connected directly to the battery 44 and a second solenoid 52 which in turn is connected to the second valve 38 so that closing of either switch 51 or 51' shifts the second valve and causes return of the ejector as discussed above. Since the switches 51 and 51 are connected directly to the battery, the ejector may be returned at any time regardless of bucket position.

The above control system prevents accidental ejection with the bucket in other than its preferred eject posi tion. However, to permit more eflicient operation of the ejector bucket, it is desirable that the operator be able to initiate ejection at any time when the bucket is being tilted forwardly. For example, with the bucket in its carry position (see FIG. 1) the operator may tilt the bucket forwardly toward its generally horizontal position and initiate ejection as forward tilting commences. In this manner, ejection of material over the rear of the bucket would be prevented. At the same time, ejection of material from the front of the bucket could be accomplished during forward tilting of the bucket. Thus. time required for ejection is decreased and the overall operating efliciency of the bucket loader is enhanced. To permit this operation, the override means 27 is preferably a proximity switch similar and parallel to the lockout proximity switch 26 in the circuit of FIG. 6.

Referring also to FIG. 4, the override switch 27 is mounted on the vehicle structure forward of and to one side of the tilt control lever 22. The tilt control lever provides a target for closing the override switch 27 in a manner discussed above with respect to the lockout switch 26. Thus, the override switch permits either or' the switches 24 or 24' to energize the relay and first solenoid at any time when the tilt lever is in a forward position and the bucket is accordingly being tilted forwardly as discussed below. However, since it would be possible with this combination for the hydraulic control of the ejector to override the hydraulic controls for the tilt jack, the controls for the tilt jacks are associated with the ejector control valve to assure priority operation of the tilt jack over the ejector jack. Referring to FIG. 6, the tilt jack has a three-position control valve 53 which is communicated with a hydraulic fluid pump 54 by a conduit 56 and with the head end and rod end of the tilt jacks by conduits 57 and 58 respectively. The tilt control valve is positioned by the tilt control lever to a rack back position (R), a central Hold position (H) or a Forward tilt position (F). When the tilt lever is in its Hold position, the conduits 57 and 58 are isolated to prevent tilt motion of the bucket. With the tilt lever in its rack back position, the tilt control valve directs fluid from the pump to the rod end of the tilt jacks. With the tilt lever in its Forward tilt position, the tilt control valve directs fluid from the pump to the head end of the tilt jacks. The fluid inlet conduit 32 for the ejector control valve is communicated with the tilt control valve so that fluid from the pump 54 is provided directly through the tilt control valve to the ejector control valve when the tilt control valve is in its Hold posi tion. However, to prevent a hydraulic override of the ejector control valve with respect to the tilt control valve, hydraulic fluid is communicated through the tilt control valve to the ejector control valve from the rod end of the tilt jacks when the tilt control lever is in its Forward tilt position. Thus, the ejector jack is powered only by exhaust fluid from the tilt jacks during forward tilting of the bucket and operating priority of the tilt jack during that period is assured.

An alternate embodiment of the ejector control system is described with reference to FIG. 7 which illustrates a simplified version of the control system. This simplified embodiment deletes the cylinder 33, the first and second valves 37 and 38 along with the fluid conduits 39, 41, 42 and 43. (See FIG. 6.) Referring again to FIG. 7, the first solenoid indicated as 48' is connected directly to the ejector control valve so that when the first solenoid is energized, the ejector control valve is shifted to communicate fluid to the head end of the ejector jack through conduit 29 as described with respect to the first embodiment of FIG. 6. The second solenoid indicated at 52 is connected to the opposite end of the ejector control valve so that when the second solenoid is energized by closing of either switch 51 or 51', the ejector control valve is shifted to direct fluid to the rod end of the ejector jack as in the first embodiment of FIG. 6. When neither solenoid is energized, the spring loaded ejector control valve returns to a central position which prevents motion of the ejector as was also discussed above. Due to the relatively higher current required in the solenoid of this embodiment to operate the ejector control valve, both of the proximity switches would preferably be replaced by cam-actuation switches indicated at 26 and 27 in FIG. 7 because of their higher current carrying capacity. Because of the higher current capacity switches employed in this embodiment, the relay switch 49 is also deleted and the switches 24 and 24 are connected directly to the first solenoid 48.

Although the present invention has been described with particular reference to two preferred embodiments, it is readily apparent that numerous variations and alterations are possible within the ejector control system as described above. For example, the proximity switches 26 and 27 in the first embodiment of FIG. 6 could also be replaced by mechanically actuated cam switches which would permit the deletion of the relay switch 49 from that circuit. Further, each set of button switches, that is switches 24 and 51 or 24' and 51, could be replaced by a single two-position toggle switch for example. Still further, the tilt lever and lift lever could be combined into a conventional single control lever while still embodying the features of the present invention.

1 claim:

1. In an ejection control system for an ejector bucket having tilt and lift control systems and tilt and lift actuating means, the combination comprising ejector actuating means associated with the tilt actuating means, said ejector actuating means being operable to initiate ejection through an ejector control system,

lockout means associated with the ejector control system and with the bucket, said lockout means permitting ejection only when the bucket is forwardly tilted to a usual dump position, and

override means associated with the tilt actuating means and ejector control system, said override means being operable to permit ejection while the bucket is being tilted forwardly regardless of its instant position.

2. The combination of claim 1 further comprising alternate ejector actuating means incorporated with the lift actuating means.

3. The combination of claim 1 wherein the ejector control system comprises a hydraulic motor for positioning the ejector in the bucket and an electrical circuit for controlling operation of the hydraulic motor, said ejector actuating means comprising an electrical switch associated with the control circuit, said lockout means being an electrical switch connected in series with said ejector actuating switch.

4. The combination of claim 3 wherein said ejector motor is a double acting hydraulic jack having a three 6 way control valve tending toward a hold position to prevent motion of the ejector,

said ejector actuating switch is associated with the control valve through first solenoid means to position the ejector control valve for ejecting operation of the ejector, and

an ejector return switch is also incorporated with the tilt actuating means and associated with the control valve through a second solenoid means to position the ejector control valve for return of the ejector.

5. The combination of claim 4 wherein the tilt actuating means is a lever having Hold, Forward tilt and Rack back positions,

the tilt control system comprises a double acting hydraulic motor and a three position control valve for supplying hydraulic fluid to the tilt motor according to the tilt lever, exhaust fluid from the tilt motor being communicated to the ejector control valve through the tilt control valve when the tilt lever is in its Forward tilt position, and

said override means is an electrical switch parallel with said lockout switch and responsive to the tilt control lever being in its Forward tilt position to permit operation of the ejector actuating switch. 6. The combination of claim 5 wherein said first and second solenoid means are operatively associated with respective first and second valves and a cylinder controls the position of the ejector control valve in response to said valves.

7. The combination of claim 6 wherein said ejector actuating and ejector return switches are disposed on both the tilt lever and lift actuating means so that an operator may actuate or return the ejector while simultaneously operating either the tilt lever or lift actuating means, said lockout switch is a proximity switch disposed on the tilt motor to be actuated when the bucket is in a tilt position suitable for ejection,

said override switch is a proximity switch associated with the tilt lever to be actuated by the tilt control lever being in its Forward tilt position, and

a relay is electrically connected between said ejector actuating switches and said first solenoid means.

8. The combination of claim 1 wherein the tilt and ejector actuating means are independently operable.

9. The combination of claim 8 wherein the tilt actuating means includes a member which is manually posi tioned to initiate operation of the tilt control system, the ejector actuating means being an electrical switch positioned adjacent the member.

References Cited UNITED STATES PATENTS 3,140,001 7/1964 Strader 214-762 HUGO O. SCHULZ, Primary Examiner US. Cl. X.R. 

